1. Field of the Invention
The invention relates to a locking mechanism for an external optical disk drive, and in particular to a locking mechanism for releasing or locking a cover of an external optical disk drive.
2. Description of the Prior Art
Optical disk drives are becoming more popular in the market, and the optical disk drives are considered as standard equipment on personal computer for several years. Generally speaking, optical disk drives are used to read information stored on optical disks. Examples of optical disk drives are known as compact disk drives (CD-ROM drives) and digital versatile disk drives (DVD-ROM drives) in prior art. Some optical disk drives have the additional capability of being able to write data onto an optical disk, i.e., CD-RW drivers. Optical disk drives are used in music and video playback and are implemented in recording devices and other electronic devices.
In prior art, the conventional disk drives are categorized into two types: disk-tray disk drive and cover-lifting disk drive. Regarding the disk-tray type disk drive, optical disk can be placed on the disk tray when a disk tray motor pulls the disk tray to what so called pull-out position. As shown in FIG. 1, the disk-tray optical disk drive includes a rectangular-shaped slit 1 a surrounding the disk tray. However, due to the slit 1a, the disk tray may be jammed by foreign objects during loading and ejection of the optical disk.
Another type of optical disk drives has an independent housing (often referred as an external type) and is coupled to a host computer via a signal cable to transmit data to the host computer. In addition, the external optical disk drive may transmit music data to the users via an earphone cable.
FIG. 2 illustrates a conventional external optical disk drive. Referring to FIG. 2, the conventional external optical disk drive includes a cover 1, an upper housing 2 and a lower housing 3.
FIG. 3 illustrates a cover of the conventional external optical disk drive of FIG. 2. Referring to FIG. 3, the cover 1 includes a protrusion 11 extending downwardly from its front end, and an opening 12 is defined in the protrusion 11. A rotary shaft 13 is integrally formed at the rear edge of the cover 1, and a gear rack 14 is integrally formed with the rotary shaft 13 of the cover 1.
FIG. 4 illustrates the conventional external optical disk drive of FIG. 2 with the cover 1 opened. Referring to FIG. 4, the upper housing 2 is positioned at the lower housing 3. The rotary shaft 13 of the cover 1 is pivotally coupled to the upper housing 2 so that the cover 1 can be pivoted with respect to the upper housing 2 and the lower housing 3. To effectively utilize the space occupied by the external optical disk drive, the rotary shaft 13 is not located at a central portion of the rear edge of the cover 1.
FIG. 5 is a perspective view of assembly of the cover 1 and the upper housing 2 of the conventional external optical disk drive as viewed from the bottom of the upper housing 2. As shown in FIG. 5, a locking member 4 indicated by phantom line is defined on the bottom surface of the upper housing 2. When the cover 1 is closed, the locking member 4 is used to engage with the opening 12 of the protrusion 11 for the purpose of locking the cover 1. Further referring to FIG. 5, a mounting member 21 is positioned on the bottom of the upper housing 2 and is adapted to receive the rotary shaft 13 of the cover 1 and an elastic member 15. The two ends of the elastic member 15 are respectively restrained by the mounting member 21 and the rotary shaft 13 of the cover 2. The elastic member 15 is of metallic (plastic) and can be a torsion spring. Besides, the gear rack 14 is adapted to engage with a spur gear (not shown) of the upper housing 2, so the cover 1 can be pivoted about the mounting member 21 because of a torsional moment of the elastic member 15.
However, as described above, the torsional moment of the elastic member 15 is not applied at the central portion of the rear edge of the cover 1, thereby causing the deformation of the cover 1. Even worse, deformation of the cover 1 may be aggravated during shipping when the environmental temperature is high, thereby rendering the optical disk drive unusable.
Accordingly, there is a need to develop a locking mechanism for use in an external optical disk drive.